* this state parse tree, and calls the parse() method for the child
* node, with state pointing to this new child. If it does not match,
* the child is removed in the state, else it is kept, with its
* this state parse tree, and calls the parse() method for the child
* node, with state pointing to this new child. If it does not match,
* the child is removed in the state, else it is kept, with its